Mexico's Antonio Margarito has earned the reputation of being the most avoided man of the welterweight division and he showed why in a classic fight in Las Vegas as he produced a magnificent 11th-round stoppage victory at the MGM Grand to win the World Boxing Association title and inflict a first professional defeat on the Puerto Rican favourite Miguel Cotto.

Cotto was floored twice in the 11th round, prompting his cornermen to throw in the towel and leave Margarito dreaming of a multimillion-dollar fight against Oscar De La Hoya, the six-weight world champion who has said he will have one more contest before retiring at the end of the year.

Margarito, 30, showed phenomenal punch resistance as well as the relentless aggression of a man who knew this was the biggest night of his fighting life, and that his biggest pay packet to date might appear insignificant against future riches if he could only seize his opportunity.

He did so brilliantly, despite Cotto's fast start earning him an early lead. The Puerto Rican landed several shots on Margarito's chin but the Mexican simply marched forward with incessant attacks. And by the seventh round his blistering assaults were clearly taking their toll.

A left to the jaw wobbled Cotto, 27, in the closing stages of the 10th, and he was unable to recover in time for the decisive 11th. When the referee, Kenny Bayless, made his intervention, Margarito had a 6-4 lead in rounds on two of the judges' cards while the third had it level at 5-5, but Cotto was by now a spent force.

"I told my corner that I would wear him down and then knock him out," said Margarito. "That was the game plan. I got him with body shots, then hit him in the head, then knocked him out."

A tearful Cotto was taken to hospital for a precautionary check-up. Before he went he said: "This night was Margarito's night. He's an excellent fighter and he did his job better than I did."

Margarito's win puts him alongside the likes of the Filipino world lightweight champion Manny Pacquiao as a potential final opponent for De La Hoya, who has been pencilled in for an appearance at the MGM Grand on December 6. The question now must be whether the "Golden Boy" still wants to share a ring with a man who has so dramatically humbled Cotto.

The former Cuba coach Jorge Rubio is to train Amir Khan for his next fight in Manchester on September 6. Rubio trained Mario Kindelán, the amateur champion who beat Khan in the Olympic lightweight final in Athens four year ago.